Commit message: Add remaining validation to `sdca_internal.cc`

PiperOrigin-RevId: 387738010
Change-Id: I28eedcfd87a53aaf34deb075acea1f8c95470808
CVE: CVE-2021-37672
CWE: CWE-703
Vulnerability description: TensorFlow is an end-to-end open source platform for machine learning. In affected versions an attacker can read from outside of bounds of heap allocated data by sending specially crafted illegal arguments to `tf.raw_ops.SdcaOptimizerV2`. The [implementation](https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/core/kernels/sdca_internal.cc#L320-L353) does not check that the length of `example_labels` is the same as the number of examples. We have patched the issue in GitHub commit a4e138660270e7599793fa438cd7b2fc2ce215a6. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.

Project: tensorflow
File: sdca_internal.cc

Status Examples::Initialize(OpKernelContext* const context,
                            const ModelWeights& weights,
                            const int num_sparse_features,
                            const int num_sparse_features_with_values,
                            const int num_dense_features) {
  num_features_ = num_sparse_features + num_dense_features;

  OpInputList sparse_example_indices_inputs;
  TF_RETURN_IF_ERROR(context->input_list("sparse_example_indices",
                                         &sparse_example_indices_inputs));
  if (sparse_example_indices_inputs.size() != num_sparse_features)
    return errors::InvalidArgument(
        "Expected ", num_sparse_features,
        " tensors in sparse_example_indices but got ",
        sparse_example_indices_inputs.size());
  OpInputList sparse_feature_indices_inputs;
  TF_RETURN_IF_ERROR(context->input_list("sparse_feature_indices",
                                         &sparse_feature_indices_inputs));
  if (sparse_feature_indices_inputs.size() != num_sparse_features)
    return errors::InvalidArgument(
        "Expected ", num_sparse_features,
        " tensors in sparse_feature_indices but got ",
        sparse_feature_indices_inputs.size());
  OpInputList sparse_feature_values_inputs;
  if (num_sparse_features_with_values > 0) {
    TF_RETURN_IF_ERROR(context->input_list("sparse_feature_values",
                                           &sparse_feature_values_inputs));
    if (sparse_feature_values_inputs.size() != num_sparse_features_with_values)
      return errors::InvalidArgument(
          "Expected ", num_sparse_features_with_values,
          " tensors in sparse_feature_values but got ",
          sparse_feature_values_inputs.size());
  }

  const Tensor* example_weights_t;
  TF_RETURN_IF_ERROR(context->input("example_weights", &example_weights_t));
  auto example_weights = example_weights_t->flat<float>();

  if (example_weights.size() >= std::numeric_limits<int>::max()) {
    return errors::InvalidArgument(strings::Printf(
        "Too many examples in a mini-batch: %zu > %d", example_weights.size(),
        std::numeric_limits<int>::max()));
  }

  // The static_cast here is safe since num_examples can be at max an int.
  const int num_examples = static_cast<int>(example_weights.size());
  const Tensor* example_labels_t;
  TF_RETURN_IF_ERROR(context->input("example_labels", &example_labels_t));
  auto example_labels = example_labels_t->flat<float>();

  OpInputList dense_features_inputs;
  TF_RETURN_IF_ERROR(
      context->input_list("dense_features", &dense_features_inputs));

  examples_.clear();
  examples_.resize(num_examples);
  probabilities_.resize(num_examples);
  sampled_index_.resize(num_examples);
  sampled_count_.resize(num_examples);
  for (int example_id = 0; example_id < num_examples; ++example_id) {
    Example* const example = &examples_[example_id];
    example->sparse_features_.resize(num_sparse_features);
    example->dense_vectors_.resize(num_dense_features);
    example->example_weight_ = example_weights(example_id);
    example->example_label_ = example_labels(example_id);
  }
  const DeviceBase::CpuWorkerThreads& worker_threads =
      *context->device()->tensorflow_cpu_worker_threads();
  TF_RETURN_IF_ERROR(CreateSparseFeatureRepresentation(
      worker_threads, num_examples, num_sparse_features, weights,
      sparse_example_indices_inputs, sparse_feature_indices_inputs,
      sparse_feature_values_inputs, &examples_));
  TF_RETURN_IF_ERROR(CreateDenseFeatureRepresentation(
      worker_threads, num_examples, num_dense_features, weights,
      dense_features_inputs, &examples_));
  TF_RETURN_IF_ERROR(ComputeSquaredNormPerExample(
      worker_threads, num_examples, num_sparse_features, num_dense_features,
      &examples_));
  return Status::OK();
}